High-pressure studies of three polymorphs of a palladium(II) oxathioether macrocyclic complex

The three reported phases of the mononuclear macrocyclic PdII complex [PdCl2([9]aneS2O)] [(1); [9]aneS2O = 1‐oxa‐4,7‐dithiacyclononane] were each studied up to pressures exceeding 9 GPa using high‐pressure single‐crystal X‐ray diffraction. The α‐ and γ‐phases both exhibit smooth compression of the unit‐cell parameters with third‐order Birch–Murnaghan bulk moduli of 14.4 (8) and 7.6 (6) GPa, respectively. Between 6.81 and 6.87 GPa β‐[PdCl2([9]aneS2O)] was found to undergo a reversible transition to a phase denoted as β′ and characterized by a tripling of the unit‐cell volume. Across the phase transition, rearrangement of the conformation of the bound macrocycle at two of the resulting three unique sites gives rise to an extensively disordered structure. Three polymorphs of a palladium(II) macrocyclic complex were studied using high‐pressure single‐crystal X‐ray diffraction to > 9 GPa, with one polymorph exhibiting a phase transition and conformational rearrangement.